1. Field of the Invention
The invention relates to a non-volatile memory and a fabrication method thereof, and more particularly, to a resistive non-volatile memory and a fabrication method thereof.
2. Description of the Related Art
Memory devices are typically divided into volatile and non-volatile types. With volatile memory devices, such as DRAM or SRAM, a continuous power supply is required to store data. For non-volatile memory devices, such as ROM, data can be stored therein for long periods of time without power supply.
As mobile phones, digital cameras, personal digital assistants (PDAs), notebooks, and other portable electronic devices become more popular, non-volatile memory devices are widely applied therein due to their ability to retain stored data without requiring power supply and low energy consumption. Among non-volatile memory devices, flash memory is currently popular. As the semiconductor technology improves, flash memory devices face challenges of high operating voltage (causing difficulty for device size conservation) and gate oxide thinning (causing unsatisfactory retention time). Thus, many new non-volatile memories have been developed to replace flash memories. Among these, resistive non-volatile memory provides high write and erase speeds, low operating voltage, long retention time, simple structure, low power consumption, small size, and low cost.
FIG. 1 is a schematic diagram of a conventional resistor type non-volatile memory 10, disposed on a substrate 12, comprising a dielectric layer 14, a bottom electrode 16, a resistor layer 18, and a top electrode 20. The bottom electrode 16 comprises a platinum film. The resistor layer 18 comprises a chromium (Cr) doped strontium titanate single crystal and provides reversible resistance switching.
However, according to conventional methods, fabrication of the resistor layer 18 still presents problems. For example, two methods are typically used. In one, a single crystal structure of SrTiO3 is formed with an orientation (100) and then undergoes flame fusion to form a Cr doped SrTiO3 single crystal. Alternatively, a pulse laser sputtering process is used to grow a Cr doped SrZrO3 film. However, the single crystal structure used in the previous method generates high cost. The latter method is not suitable for large area films. Thus, neither method can meet the requirements of mass production.